This invention relates to the technical field of an image input apparatus used in a digital photoprinter or the like which reads an image on a film photoelectrically to obtain a print (photograph) having the image reproduced thereon.
Currently, the image recorded on a photographic film such as a negative film or a reversal film (which is hereinafter referred to as xe2x80x9cfilmxe2x80x9d) is printed to a light-sensitive material (photographic paper) by xe2x80x9cdirect exposurexe2x80x9d (or analog exposure), in which the image on a film is projected onto the light-sensitive material to perform areal exposure.
A printer that relies upon digital exposure has recently been commercialized. Called a xe2x80x9cdigital photoprinterxe2x80x9d, the apparatus operates in the following manner: the image recorded on a film is read photoelectrically; the image is then converted to a digital signal and subjected to various image processing steps to produce image data for recording; a light-sensitive material is exposed by scanning with recording light modulated in accordance with the image data, whereby an image (latent image) is recorded; the necessary processing is done to produce a (finished) print.
In the digital photoprinter, the image recorded on a film is converted to digital image data, which is then processed to determine the conditions for exposure to be performed in printing; hence, the correction of drop-outs or blocked-ups in image such as washed-out highlight or dull shadow due to photography with back light or an electronic flash, sharpening, or the correction of color or density failure can be effectively performed to produce prints of very high quality that have heretofore been unattainable by conventional direct exposure. What is more, by image data processing, a plurality of images can be assembled into one composite image or a single image can be divided into more than one image and even characters can be assembled; thus, prints can be outputted after editing/processing is done in accordance with a specific use.
With the digital photoprinter, the desired image can not only be outputted as a finished print (photo); the image data can also be supplied to a computer or stored in a recording medium such as a floppy disk; thus, the image data can be utilized in various applications other than photography.
Having these capabilities, the digital photoprinter is basically composed of an image input apparatus including a scanner (image reader) for photoelectric reading of the image recorded on a film and an image processor that performs image processing on the thus read image to produce output image data (conditions for exposure), as well as an image output apparatus including a printer (image recorder) that performs scan exposure on a light-sensitive material in accordance with the image data from the image input apparatus and a processor (developing machine) that subjects the exposed light-sensitive material to development and other necessary steps to produce a finished print.
In the scanner, reading light issuing from a light source is allowed to be incident on the film to produce projected light carrying the image recorded on the film and the projected light is focused through an imaging lens on an image sensor such as a CCD sensor, whereby photoelectric conversion is effected to read the image from the film; after optionally being subjected to various image processing steps, image data from the film (image data signal) is sent to the image processor.
The image processor sets the conditions for image processing on the basis of the image data that has been read with the scanner; the image processor then performs image processing on the image data in accordance with the thus set conditions and supplies the printer with output image data (exposure conditions) for image recording.
In the printer, if it is of a type that relies upon exposure by scanning with light beams, the latter are modulated in accordance with the image data sent from the image processor and deflected in a main scanning direction; at the same time, a light-sensitive material is transported in an auxiliary scanning direction perpendicular to the main scanning direction to expose to the light beams carrying the image, thereby forming a latent image. The image is then subjected in the processor to development and other processing steps in accordance with the light-sensitive material, thereby producing a finished print (photograph) reproducing the image recorded on the film.
When the image input apparatus is used to perform photoelectric image reading in the aforementioned digital photoprinter, prescanning (pre-reading) for reading an original at low resolution is usually performed prior to image reading (fine reading=fine scanning) for obtaining output image data. The image data obtained by prescanning is used to set for each frame reading conditions for fine scanned (image) data and (image) processing conditions for processing the image data obtained by fine scanning to produce the output image data. The processing conditions are adjusted as appropriate by the verification that the operator performs as required.
In accordance with the type of the original to be read, reading conditions for prescanned data, specifically the light quantity of reading light (light quantity of a light source), the value to which a variable diaphragm is stopped down, and the storage time of an image sensor such as a CCD sensor are preliminarily determined so that the image sensor is not saturated even at a possible minimum density. Image reading is thus performed under the specified reading conditions in accordance with the type of the original.
On the other hand, reading conditions for fine scanned data are set for (the respective frames of) each image on the original on the basis of the image data obtained by prescanning so that the output from an image sensor such as a CCD sensor saturates at a density a little lower than the minimum density of the image on the original.
In addition, the pixel density for reading is also different between prescanning and fine scanning. The scanning speed is further different when reading is performed by slit scanning.
That is, the reading conditions for prescanned data are different from those for fine scanned data. In order to obtain an image appropriately finished with the fine scanned (image) data, the latter is processed under the image processing conditions that were set based on the prescanned (image) data read under different reading conditions. The processed image data is then converted to output image data. Therefore, there are cases where the output image after processing of the fine scanned data can not be an image supposed to be obtained based on the prescanned data due to difference of the reading conditions between the two kinds of data, which prevents production of images having a specified image quality.
The present invention has been accomplished under these circumstances and has as an object providing an image input apparatus capable of preventing any reduction in image quality due to the difference of the reading conditions between prescanned data and fine scanned data and ensuring consistent outputting of high quality images.
In order to attain the above object, the present invention provides an image input apparatus in which image data on an original is read photoelectrically and subjected to specified image processing steps to obtain output image data, wherein said apparatus comprises:
reading conditions setting means for determining reading conditions for fine reading in accordance with the image data obtained by pre-reading which is an image reading performed under specified conditions prior to the fine reading for obtaining the output image data;
storage means for storing the image data obtained by the fine reading performed according to the reading conditions set by said reading conditions setting means;
processing conditions setting means for setting image processing conditions to obtain the output image data in accordance with the image data obtained by said fine reading; and
image processing means for receiving the finely read image data from said storage means and for subjecting the received image data to the image processing steps according to the image processing conditions set by said processing conditions setting means.
Verification job is preferably performed using said finely read image data.
Preferably, said processing conditions setting means sets at least one of the image processing conditions including color balance adjustment, density adjustment and gradation adjustment which are severally performed for each image region.
Preferably, said processing conditions setting means uses the image data obtained by the fine reading performed for a plurality of frames to set the image processing conditions for each frame, taking into consideration differences of the reading conditions for fine reading between the frames.
Preferably, separate reading means provided in a direction in which said original is transported are used to perform said pre-reading and said fine reading, while transporting said original.